Turbidity detector



Dec. 26, 1950 A. D. WAY

TURBIDITY DETECTOR Filed July 21, 1947 ITI-l ARNOLD D. WAY

INVENTOR.

Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE rnnrmzsilnrncron A'rnold D. Wa'y, Bronxville, N. Y., assignor to The Permutit Company, New York, N. Y., 'a corporation of Delaware Application J'uly 21, 1947, Selal'No. '762,227

Z'Claims. ll

This invention relates to turbidity detectors; and it comprises a guide tube "for producing a freely and smoothly flowing sheet of liquid of uniform thickness, a light source projecting a beam of light through said sheet, and a light- 'sen'sitive Cell receiving light shining through said sheet; 'all 'as more fully hereinafter set fforth and as claimed.

In rmany arts and processes it is desirable to determine the vturbidity of vfluids, and various devices involving the use 'of light-sensitive cells for such determination of turbidity have been suggested. There is room for improvement, however, in thereliability of such devices and in the amount lof attention required to maintain them in operation. For instance, the liquid being tested has a tendency to deposit some of the turbidity which it carries `on any surface vpast which it ows. When the beam of light passes through walls made of glass or other transparent material and used to conne the liquid being tested, such walls become gradually coated, thus 'interfering' with and falsifying 'the measurement.

It is the object of my invention to provide a 'more reliable device for `detecting turbidity which requires 'a minimum of attention; and more particularly to provide a device in which the li'ght beam does not pass through any surfaces which are wetted by the liquid being tested. K i The manner in which this object is achieved is shown in the appended drawing in whichi Fig. l is a View, partly inisection, of a turbidity detector in accordance with my invention;

Fig. 2 is a View, in section along lines 2-2 of Fig. 1, of the guide tube, on an enlarged scale; and

Fig. 3 is a View, insection along lines 3-3 of Fig. 2.

Like numerals refer to like parts throughout the several views.

As shown in Fig. 1 the apparatus has a casing I D provided with removable covers II and I2. Within the casing Il) and fastened thereto by means of screws I4 is a cross-shaped body I3, a gasket I5 being provided between the top of the body and the casing I9. The body I3 has a central passage I9 and two side extensions I'I and I8 on the ends of which lenses I9 with gaskets 29 are attached by means of screw covers 2 I.

Within the passage I6 is mounted a guide tube shown in greater detail in Figs. 2 and 3. The guide tube 25 is fastened to a ange 24, as by braging or soldering. The upper portion of the guide tube 25 is of circular cross section and its lowermost portion is attened at 26. Within the attened portion there are two wedge shaped filler pieces 21 held in place by rivets 28. The vguide tube 25 thus provides a passageway 39 which changes from a circular cross section at the top to a rectangular cross section within the portion 26. IThe part of thepassageway within the n att'ened portion 26 is of uniform thickness but 'of downwardly `decreasing width because of the presence of the filler pieces v2'I. The flattened sides of the portion 26 are cut out at 29. I

The guide tube is 'set into the body I3 with the flange restingfon gasket I5. An additional gasket `3| i's placed `on top of the lange 2li, and a companion iiange 32 attached to the body by means of bolts 33 holds the flange 24 in place 'and provides an inlet into the top of passage v39 for liquid to be tested The lower end of the body I3 is threaded at `35 for lconnection of a pipe to c'arry the tested liquid away.

Within the 'casing Ill is av light source 31 mounted "on a hinged support 38 and so arranged as to throw a bearnvof light through the lenses II9 and the cut='outs 29. A1 lightsensitive cell 39 is mounted on a bracket Al0 in such a position as Vto receive light shining through the cut-outs 29.

in operation, liquid to be tested enters through 'the companion flange 32 into the passageway 30 andflowspas't the Icut-outs 29 in the `form of a freely and smoothlyY flowing sheet of uniform thickness becauseo'f the particular shape of the passageway 3D. Light shining from the source 31 thus passes the lenses I9 and the sheet of liquid flowing past the cut-outs 29 before it reaches the light-sensitive cell 39, the intensity of light reaching the cell 39 therefore depending on the amount of turbidity present in the liquid.

When the liquid is free of turbidity the light reaches cell 39 with maximum intensity. The cell then generates a relatively strong electric current. If any turbidity appears in the liquid the intensity of light reaching the cell 39 diminishes and the strength of the electric current generated by the cell 39 is reduced accordingly. The intensity of the electric current generated by cell 39 is thus a measure of the turbidity present in the liquid being tested and may be utilized in known ways to actuate a signal or control device. A suitable arrangement of electrical devices is shown, for example, in the U. S. Patent 2,351,235 to E. Pick, dated October 24, 1944, but other circuit arrangements may be employed. The electrical devices are advantageously mounted within the casing Ill on the hinged support 38 and the bracket 49.

My apparatus may, for instance, be used in connection with the treatment of water in accordance with the process disclosed in the U. S. Patent 2,021,672 to Spaulding, dated November 19, 1935. In such process the water, when properly treated, has a relatively low turbidity of the order of 5-10 parts per million. When the process is not functioning correctly the turbidity of the treated water rises and its measurement thus provides an excellent check on the performance. In such Spaulding process there is a filter blanket of highly concentrated sludge having a turbidity of the order of several thousand parts per million. Such blanket continues to build up as the process is carried on and it is necessary from time to time to blow off a portion of it so as to keep such blanket within proper bounds. My apparatus may also be used, by sampling the water at a level corresponding to the maximum desired sludge blanket level to indicate by a signal when such maximum level has been reached, or to automatically open a blowoff valve.

My apparatus may, of course, be used for determining the turbidity of liquids other than water, and it may also be employed for determining the intensity of color instead of turbility.

The beam of light does not pass through any surface wetted by the liquid being tested, the lenses 20 being so located that they are not exposed to wetting. Such lenses are not essential to the functioning of my detector, but are advantageously provided to prevent excessive humidity within the casing I9 which might be harmful to the electrical devices installed therein. When used for this purpose only, the lenses may have parallel sides, but, if desired, they may be so shaped as to concentrate the light beam projected from the source 31 toward the cell 39.

The important function of the guide tube 25 is to produce a freely and smoothly owing sheet of liquid of uniform thickness, free of waves and spray which would aiect the passage of light.

While I have shown the guide tube as made from a cylindrical tube by attening a portion, inserting ller pieces and cutting out ther fiattened portion, it may, of course, be made in l other ways to provide a downwardly converging passageway ending in a at portion with parallel sides facing the light source and the lightsensitive cell. Thus, the guide tube might be made as a casting, or molded from hard rubber or plastic. A passageway one-eighth inch thick and ve-eighths inch wide at its lowermost end will give good results with a iiow of liquid at a rate somewhat less than one gallon per minute.

While I have shownY and described what I consider the preferred arrangement, modifications may be made without departing from the spirit of my invention and reference is therefore made to the following claims for a denition of the scope of my invention.

What I claim is:

1. A turbidity detector guide tube having a straight vertical passageway therein, the lowermost portion of said guide tube being attened to provide two parallel sides and reduce said passageway to uniform thickness, two wedge shaped filler pieces within said flattened portion so placed as to make the width of said passageway downwardly converging in width, matching cut-outs in both said parallel sides, and means for admitting liquid to the upper end of said vertical passageway.

2. A turbidity detector comprising a crossshaped body having a horizontal and a vertical passage therein, a guide tube mounted in said vertical passage and having a vertical passagewayntherein, said passageway having its lowermost portion of rectangular cross-section with two sides parallel to each other, cut-outs in said parallel sides aligned with said horizontal passage to permit light to pass through said horizontal passage, means for admitting liquid to the upper end of said vertical passageway, and lenses mounted on said body on either side of said cut-outs.

ARNOLD D. WAY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,053,665 Spencer Feb` 18, 1913 1,496,635 Higley June 3, 1924 1,785,392 Sawford et al Dec. 16, 1930 1,785,393 Sawford Dec. 16, 1930 1,809,999 Wier June 16, 1931 1,814,020 Armstrong July 14, 1931 1,979,649 Stephenson Nov. 6, 1934 1,994,768 Haven et al Mar. 19, 1935 2,026,743 Kurtz Jan. 7, 1936 

